Since the writeback patches are now (at last!) in mainline, I renamedthis branch from writeback-postmerge to just plain writeback. The firstfour patches are identical to the ones from friday, and then I addedthree more patches. Two of them are cleanups to better separate theWB_SYNC_NONE and WB_SYNC_ALL writeback paths, the latter is a fix forwhen a bdi is destroyed whilst inodes are still attached. I don't seea much better way to fix this at the moment, if inodes get requeuedat sync time, then it would complicate exit quite a lot. So justmove those entries to the default_backing_dev_info, which can handlethem at any time.